Brazing Carbides

We used to braze our carbides on to tool holders by hand. Just an acetylene torch and heat till cherry red and then add your brazing metal. We had some 200 to 250 tools to braze every month for our in-house machine shop so it was reasonably high volume.

It must however depend on what you want to use them for if this method is acceptable, we only cut pvc piping with it.

I cannot answer your second question as we never did that before so hopefully someone else can.

In my early days I worked as a toolmaker and we did some brazing of carbide. What we used was a shim stock material that was coated with silver solder, this would give us a somewhat accurate positioning of the "carbide" and also because we wanted the complete piece to be bonded without voids it provided a better flow of soldier, if you have to use a rod or stick you may get voids depending on how large your carbide piece is. if you have to used the stick type, you may want to pre-solder the steel prior to inserting the carbide.

For our applications we used an oxy-acetelyne torch and put the steel, carbide and shim solder in place and held it lighty in place and heated from the bottom of the steel until the solder would reach its melting point( make sure if you use the shim, you let it melt completely, you will be able to see this happen during the process). The surfaces of the Carbide, shim solder, and the steel need to be cleaned thoroughly(you will need to used a cleaner to remove all grease and oils, don't touch the surfaces with your fingers, your fingers have oils in them that can affect the process). You don't have to overheat your steel for the solder to melt, but silver solder needs to be hotter than normal solder for it to reach it's melting point, regular propane will not create enough heat, this is why we used oxy-acetelyne torches.

S.A.E 2340 is a recommended steel. There is information related to this application written in the machinerys handbook, if you have the 22nd addition it is on page 2203. You can find out other reccomendations in the machinery's other eddtions as well, it may be on different pages though. You may find one of these books at a local library.

Keep in mind safety, confirm the types of material and carbide and solders being used will provide you with the proper strenght for your application.

Good luck!

Yes I do agree, my mistake they had Borax listed in the handbook and I forgot to put it in. Thanks for the reply.

Good advice Madman. You forgot one thing. Dab some flux on both surfaces. I point this out only because not everybody is an expert in doing it.

I once worked at a plant where they made piston and sealing rings, every kind but automotive. they wired the sealing tongues to the ring with silver solder and flux. They then went to an induction welder.

The problem with induction welders is that they are very expensive. I know because I have surfed the web looking for them. Production would have to be very high to justify one.

Silver solder comes in hundreds of types. I suggest you go on the web and find manufacturers reccomendations for the best alloy.

I am not sure about this but my experience has been that you don't have to worry about overheating the carbide, just don't dip it in water to cool it.

Some carbide materials blister if you heat them far over the cherry red. It was a while ago, some 20 years by now, so maybe the materials have changed but we never heated much further then cherry red.

That long ago I cannot exactly remember what and how we did it but we must have used some powder flux. It seems daft not to as it makes life so much easier. Just clean well afterwards.

STAYCLEAN is the flux you are looking for, it is a liquid I believe its in a white squeeze bottle --red lettering